Noise generating transducers are used for converting an input electrical signal to an output audible tone. Currently, noise generating transducers are used in the alarm devices of various types of machines and vehicles. Earth moving machines, utility vehicles, garbage trucks, and school buses are all examples of machines or vehicles that may use an alarm device. Alarm devices are typically used to warn people in the surrounding area that a machine or a vehicle is moving, such as in a backward motion.
An alarm device having a conventional noise generating transducer with an attached moving coil type of diaphragm is shown in FIG. 1, as an example. The diaphragm 10 is typically made of a rigid plastic material in the shape of a spherical dome. Along the circumference of the diaphragm 10 is a corrugated ring like structure 15. The corrugated ring like structure 15 is designed to expand and contract, allowing the diaphragm 10 to move. The moving coil 20, is attached to the diaphragm 10. Flexing wire leads 25a-b, connected to each end of the attached moving coil 20, are used to input and output an electrical signal. The attached moving coil 20 and the flexing wire leads 25a-b are typically made of a braided copper wire.
The conventional noise generating transducer 5 includes a ceramic ring permanent magnet 30 located radially around the inside rim of the transducer housing 35. A first magnetic member 40 is also located radially around the inside rim of the transducer housing 35, and a second magnetic member 45 is located near the center of the transducer housing 35 and beneath the diaphragm 10. A gap between the top of the second magnetic member 45 and the diaphragm 10 allows the diaphragm 10 to move.
A mechanical force on the attached moving coil 20 is produced by the interaction of the current, from an electrical signal input, to the attached moving coil 20 and the magnetic field disposed radially across the gap between the first magnetic member 40 and the second magnetic member 45. An audible tone is produced by the oscillating movement of the diaphragm 10.
However, with the moving diaphragm type of alarm device, problems with the flexing wire leads 25a-b may occur. Due to the flexing wire leads 25a-b being connected to each end of the attached moving coil 20, the flexing wire leads 25a-b have to move with the oscillation of the diaphragm 10. The point of connection between the flexing wire leads 25a-b and the attached moving coil 20 may sever due to the stress placed on the connection by the movement. Also, a crimp may form in the flexing wire leads 25a-b due to the flexing wire leads 25a-b being forced to move with the oscillating movement of the diaphragm 10. The crimp may eventually lead to a breakage of the flexing wire leads 25a-b.
The present invention is directed to overcoming one or more of the problems as set forth above.